This thesis provides an approach to incorporate natural composites like Flax Fiber using a resin with 30% bio-content to enhance the packaging boxes made of corrugated cardboard. The objective of introducing natural composite skins is to reduce/eliminate the compressive loading subjected to the boxes while stacking in warehouses.

Corrosion of steel reinforcement has been identified as one of the major problems facing many existing reinforced concrete structures including bridges. The exposure to aggressive environmental conditions such as those with high concentrations of chloride ions due to the use of de-icing salt in cold regions or high concentrations of carbon dioxide due to increased greenhouse gas emissions, accelerate the initiation process of corrosion. As corrosion initiates, the structural performance in terms of load-carrying capacity, ductility, and service life deteriorate over time. Coupling the effect of reinforcement corrosion with service loads may further weaken the structural performance of reinforced concrete bridges due to the presence of transverse load-induced cracks. Accordingly, a research program was conducted to evaluate the structural performance of reinforced concrete beams subjected to coupled effects of service loads and reinforcement corrosion. The research project consisted of combined experimental and numerical investigations. The experimental phase consisted of tests of nine small-scale beams and six large-scale beams. The beams were designed, constructed, instrumented, and loaded under a four-point load test. The primary test variables were the applied corrosion current density, level of corrosion, and level of sustained loading as percentage of beam ultimate capacity (0% Pu, 40% Pu, and 60% Pu). The corrosion level of steel reinforcement was quantitatively assessed using gravimetric weight measurements and three-dimensional laser scanner technique. Test results indicated that failure of corroded RC beams was brittle due to premature rupture of corroded steel bars, which was attributed to the development of localized corrosion at the sections with flexural cracks in beams. Furthermore, it was found that beams subjected to higher levels of service loads, experienced further reductions in ultimate load capacity and ductility. In addition, tensile tests were used to evaluate the effect of corrosion on the mechanical performance of steel bars retrieved from the corroded beams. It was found that the tensile strength of corroded steel bars, based on nominal sectional area, was reduced with the increase of corrosion levels. In contrast, the tensile strength, based on minimum sectional area, was not influenced by the non-uniform distribution and localization of corrosion. In fact, there was a slight increase in strength with the increase of corrosion levels. The numerical phase consisted of finite element analyses of beams using DIANA FE analysis software. A simplified approach was implemented to introduce the damage induced by corrosion into two-dimensional nonlinear FE models, based on the experimental testing of corroded beams and corroded steel bars. The analyses were reasonably accurate in predicting cracking patterns, residual load capacity, residual ductility, and failure modes of corroded beams. Subsequently, the validated model was used to conduct a parametric study on the level of service loads, level of corrosion, strength of concrete, and tensile reinforcement ratio. It was found that the FE model of corroded beams was strongly influenced by the level of service loads, level of corrosion, and tensile reinforcement ratio.

>Magister Scientiae - MSc / The growth of the Internet has led to many interesting developments for both educational and commercial purposes. In this project an attempt was made to use the Internet for a research purpose to facilitate the determination of the thermal stability of diffusion barriers. Another purpose of this thesis is to investigate the teaching and training use of the Internet through the development of online interactive tools and activities as well as materials. The training aspects are mentioned as it is hoped that this thesis can serve as a form of documentation of the use of the Internet, while the central part was the determination of thermal stability of TiN, TaN and TiW diffusion barriers on Ag. The fact that most advanced instruments are computer driven or can be interfaced with a computer was exploited to set up a virtual laboratory facility through which sophisticated and scarce instrumentation can be remotely accessed. The major piece of equipment that forms part of the laboratory is a four-point probe furnace at Arizona State University, Tempe, USA. The Internet made it possible to use the facility to perform an online experiment to determine the effectiveness of different diffusion barriers for silver metallisation. This was accomplished by measuring the resistance of the different samples remotely over the Internet through the control of the four-point probe furnace at Arizona State University. Four types of analysis were used to determine the thermal stability of the diffusion barriers, namely the Scanning Electron Microscopy, Rutherford Backscattering Spectrometry, X-Ray Diffraction and resistivity measurements. Similar facilities exist at Oak Ridge National Laboratory, Tennessee, USA, where a range of different electron microscopes can be accessed remotely via the Internet. The measurements of the diffusion barriers form the main part of this work. However, the other aspects required for the use of the Internet in such a system, such as the development of a website to receive and upload scanning electron microscopy (SEM) images, the development of the virtual scanning electron microscope and the learning of the Virtual Reality Markup Language are also included.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis provides an approach to incorporate natural composites like Flax Fiber using a resin with 30% bio-content to enhance the packaging boxes made of corrugated cardboard. The objective of introducing natural composite skins is to reduce/eliminate the compressive loading subjected to the boxes while stacking in warehouses.

This master’s thesis describes an experimental program investigating the strengthening of beams of glued laminated timber with composite reinforcement. The work compares the behavior of beams reinforced with composite reinforcement with unreinforced beam and with solid timber beam. The work also deals with identifying and evaluating the physic-mechanical properties of materials.

No description available.

This thesis was most concerned with the mechanical response to irradiation of two in-house produced oxide dispersion strengthened (ODS) steels and two non-ODS coun- terparts. The steels, manufactured by Dr. M. J. Gorley (University of Oxford), were me- chanically alloyed from gas-atomised Fe-14Cr-3W-0.2Ti, with the addition of 0.25Y₂O₃ powder in the case of the ODS variants. The powders were hot isostatic pressed at consolidation temperatures of 950 °C and 1150 °C. The four steels were designated 14WT 950 (non-ODS), 14YWT 950 (ODS), 14WT 1150 (non-ODS) and 14YWT 1150 (ODS), and were used in the as-produced condition. Initially, the macroscale elastic modulus and yield stress were determined using a four-point flexure test, employing digital image correlation (DIC) as a strain gauge. The microcantilever size eects were then characterised, and it was determined that the yield stress signicantly diverged from macroscale values at microcantilever beam depths of < 4.5 μm. Using knowledge of this, the in-house produced alloys were irradiated with 2 MeV protons at the Surrey Ion Beam Centre (University of Surrey, UK) to a displacement damage of ∼ 0.02 dpa and 0.2 dpa (Bragg peak). This was to produce a deep irradiated layer for the fabrication of large microcantilevers with reduced size effects. The cross-sectional surface of the irradiated layer was then exposed and inclined linear arrays of 250 nm deep indents were placed across the damage prole. 14WT 1150 (non-ODS) revealed a clear proton damage prole in plots of hardness against irradiation depth, 14WT 950 (non-ODS) also showed modest hardening in the region of the Bragg peak. No appreciable hardening was observed in either 14YWT specimens, attributed to the fine dispersion of nanoscale oxides providing a high number density of defect sink sites. However, a large bimodal variation in hardness was measured in both ODS variants. This was investigated using EBSD and EDX, and was determined to be caused by a pronounced heterogeneity of the microstructure. While Hall-Petch strengthening and changes in the local chemistry had some effect on the measured hardness, the most likely cause of the large variation in local hardness was heterogeneity in the nanoscale oxide population. Microcantilevers were fabricated out of the irradiated layer cross-section in 14WT 1150 and 14YWT 1150. Larger microcantilevers, with ∼ 5 μm beam depth, were placed with their beam centre at ∼ 0.026 dpa. Smaller microcantilevers, with ∼ 1.5 μm beam depth, were placed with their beam centre at the Bragg peak, 0.2 dpa. Both the large and the small microcantilevers fabricated in 14WT 1150 (non-ODS) displayed significant irradiation hardening. In the ODS variant, 14YWT 1150, irradiation hardening appeared to be reduced. The work in this thesis successfully showed that it was possible to extract a close approximation of the macroscale yield stress from shallow irradiated layers, providing that the irradiation condition is carefully chosen in response to known size dependent behaviour. This thesis also investigated the size dependent behaviour of microcantilevers using a lengthscale dependent crystal plasticity UMAT, developed by Dunne et al. and implemented within ABAQUS 6.14-2 commercially available nite element software. The simulation of the GND density evolution with increasing plastic strain allowed their contribution to the microcantilever size effect, through mobile dislocation pinning, to be determined. This novel approach to modelling size effects in three dimensional finite element microcantilever models demonstrated that while it was possible to simulate a lengthscale-dependent response in finite element microcantilever models, the constitutive equation for the plastic velocity gradient needs to be more physically based in order the match the experimentally derived results; for example, a lengthscale-dependent term relating to the dislocation source density of the material. Although the apparent reduction of irradiation hardening in ODS in-house produced alloys showed great promise, these alloys also displayed a large amount of scatter in measured hardness and yield stress, attributed to the pronounced heterogeneity in the microstructure. Alloys with such signicant microstructural heterogeneity are not suitable for engineering or commercial use.

The Main Street Four Point Approach to commercial revitalization has been applied successfully in thousands of communities across the U.S. Starting in 1995, citywide coordinated programs began applying the balanced points of organization, design, economic restructuring and promotion to urban environments. This thesis focuses on the opportunities and challenges present in five citywide Main Street programs in Boston, Baltimore, Washington D.C., Orlando and Portland through quantitative inquiry and interviews with program administrators. This thesis discusses density, capacity, volunteerism, vernacular culture, and politics as emergent themes of the urban application of the Main Street Approach and recommends expanding the breadth of definition and flexibility of each of the Four Points as to be more applicable and successful in the citywide context.

A reciclagem de pavimentos com adição de cimento Portland é uma técnica que permite reutilizar estruturas degradadas de pavimentos flexíveis na conformação de uma nova camada estabilizada. Seu dimensionamento, no Brasil, tem sido abordado de forma empírica. Entretanto, os métodos racionais desenvolvidos para pavimentos semirrígidos estão baseados principalmente na previsão da vida de fadiga das camadas cimentadas, associada ao nível de deformação atuante na sua fibra inferior. Com o intuito de contribuir no desenvolvimento de um método de dimensionamento de pavimentos com camadas recicladas com adição de cimento, a pesquisa relatada nesta dissertação teve como objetivo principal o estudo laboratorial do comportamento a fadiga de misturas constituídas por fresado asfáltico (20%, 50% e 70%), brita graduada e cimento Portland (teores de 2% e 4%). O programa experimental foi baseado no protocolo para caraterização de materiais cimentados da Austroads (2008; 2012), para ensaios estáticos e de fadiga, além de recomendações para caracterização flexural da JCI (1984), procurando-se avaliar a sua aplicabilidade. Os ensaios de fadiga foram realizados em vigotas com dimensões 10 cm x 10 cm x 40 cm, curadas por pelo menos 28 dias. O modo dos ensaios foi o de tensão controlada como função da resistência à tração na flexão, previamente determinada. O sistema de carregamento é conhecido como fadiga a 4 pontos. Foram obtidos modelos de fadiga em função da tensão de tração atuante, da deformação inicial e da energia dissipada inicial. Os resultados dos ensaios estáticos indicam a predominante influência do teor cimento na resistência a tração na flexão das misturas (valores entre 0,21 MPa e 1,53 MPa), enquanto a porcentagem de fresado tem efeito significativo na deformação de ruptura, tornando as misturas mais dúcteis, e no Módulo de Elasticidade Flexural (que variou entre 1483 MPa e 12800 MPa). No caso dos ensaios de fadiga, os Módulos de Resiliência Flexural iniciais (valores entre 2913 MPa e 7725 MPa) mostraram-se mais dependentes do teor de cimento e independentes do nível de tensão. Nos modelos de fadiga obtidos, os valores dos exponentes de dano por deformação variaram entre 7 e 15, sendo próximos aos relatados pela Austroads para materiais cimentados. Esses modelos foram empregados na modelagem de estruturas de pavimento com camadas de base reciclada, de espessura de 18 cm a 40 cm, visando quantificar o efeito do teor de cimento e da porcentagem de fresado na vida de fadiga, bem como das espessuras da camada reciclada e da nova camada asfáltica sobrejacente. Observou-se que espessuras de camada reciclada inferiores a 30 cm terão curta vida de fadiga. Por outro lado, também ficou evidenciado que a vida de fadiga dessa camada depende significativamente da espessura da nova camada asfáltica sobrejacente, recomendando-se espessuras de no mínimo 10 cm. Finalmente, destaca-se que o volume de dados gerado durante os ensaios de fadiga, e seu processamento por meio de algoritmos desenvolvidos na pesquisa, permitiram abordar conceitos de energia dissipada, como aproximação à definição de critérios de micro e macrofissuração, o que mostrou a utilidade deste tipo de abordagem para futuras pesquisas. / Full-depth reclamation with Portland cement (FDR-C), is a technique allowing the reuse of flexible pavements damaged structures, in order to build a new stabilized layer. In Brazil, pavement design with FDR-C has been determined by empirical approaches. However, mechanistic approach developed for semi-rigid pavements mainly use fatigue relationships based on deformations occurring at the bottom of the cemented layer. In order to develop a pavement design method with FDR-C materials, this research work aimed to study, in laboratory, the fatigue behavior of FDR-C mixtures, for three cement grades (2 %, 4 % e 6 %) and three RAP (Reclaimed Asphalt Pavement) percentages (20 %, 50 % e 70 %).The experimental program was based on the protocol for the characterization of cemented materials of the Austroads (2008; 2012), for static and dynamic tests, and on the recommendations for flexural characterization of concrete reinforced with steel fibers, of the JCI (1984), evaluating the availability of these procedures. Fatigue tests were executed using beams (10 cm x 10 cm x 40 cm), static compacted and with a minimum curing time of 28 days. Stress controlled mode was used, based on flexural strength, previously determined. Loading system was a four-point bending test. Were developed fatigue strain, stress and dissipated energy relationships. Static tests results show that cement is the principal influence on the flexural strength of the mixtures (0.21 MPa up to 1.53 MPa), while the RAP have a major effect in the increasing of the tensile strains making it more ductile (flexural elastic modulus were 1483 MPa up to 12800 MPa). In the case of fatigue tests, flexural modulus were more dependent on the degree of cementation (2913 MPa up to 7725 MPa), and not on the applied stress level. About the fatigue models of FDR-C mixtures, strain damage exponents (7 up to 15) were similar to those reported by Austroads. Laboratory models based on strain were used in modeling of pavement structures, with a FDR-C base layer. Results showed benefits of thickness in FDR-C mixtures and asphalt layers (18 cm up to 40 cm), in order to evaluate the effect of the cement and RAP content on fatigue life, and FDR-C new asphalt thickness as well. This model highlights that FDR-C with a thickness inferior than 30 cm will have a shorter fatigue life. On the other side, was showed that the fatigue life of this layer mainly depends on new hot mix asphalt thickness layer (thickness recommended up to 10 cm). Finally, the volume of data generated during the fatigue tests and his processing through algorithms developed in research allowed using dissipated energy criteria as an approximation of the definition of micro and macro-cracking limits which indicate the utility of this methodology for future research. / El reciclaje de pavimentos con adición de cemento Portland es una técnica que permite la reutilización de estructuras degradadas de pavimentos flexibles para la conformación de una nueva capa estabilizada. Su diseño, en Brasil, ha sido abordado de forma empírica. Sin embargo, métodos racionales desarrollados para pavimentos semirrígidos están basados en la vida de fatiga de las capas cementadas, asociada al estado de deformaciones actuante en su base. Con el objetivo de contribuir al desarrollo de un método de dimensionamiento de pavimentos con capas recicladas con adición de cemento, la investigación relatada en esta disertación tuvo como objetivo principal el estudio laboratorial del comportamiento de fatiga de mezclas constituidas por fresado asfáltico (20%, 50% y 70%), base granular y cemento Portland (2%, 4 % y 6 %). El programa experimental fue basado en protocolos de caracterización de materiales cementados de la Austroads (2008, 2012), para ensayos estáticos y de fatiga, además de recomendaciones para caracterización flexural de concreto reforzado con fibras de acero de la JCI (1984), procurando evaluar su aplicabilidad. Los ensayos de fatiga fueron realizados en vigotas con dimensiones de 10 cm x 10 x cm x 40 cm, moldadas estáticamente y curadas por lo menos 28 días. El modo de carga fue de esfuerzo controlado en función de la resistencia de tracción en la flexión, previamente determinada. El sistema de carga es conocido como fatiga 4 puntos. Los resultados de los ensayos estáticos mostraron una influencia predominante del contenido de cemento respecto a la resistencia flexural de las mezclas (valores entre 0,21 MPa y 1,53 MPa), mientras que el material fresado tiene un efecto significativo en la deformación de tracción al tonar más dúctiles las mezclas, afectando módulo de elasticidad flexural (valores entre 1483 MPa y 12800 MPa). En el caso de los ensayos de fatiga, los Módulos de Resiliencia Flexural iniciales (valores entre2913 MPa y 7725 MPa) mostraron ser más dependientes del grado de cementación e independientes del nivel de esfuerzo aplicado. Los valores de los exponentes de daño por deformación en los modelos de fatiga, que variaron entre 7 y 15, fueron próximos a los relatados por la Austroads. Estos modelos fueron usados en la modelación de estructuras de pavimento con capas de base reciclada, de espesor entre 18 cm y 40 cm, buscando cuantificar el efecto del contenido de cemento y de fresado en la vida de fatiga. Se observó que espesores de la capa reciclada inferiores a 30 cm tendrán corta vida de fatiga. Por otro lado, fue evidenciado que la vida de fatiga de esta capa depende significativamente del espesor del nuevo revestimiento asfáltico, recomendándose espesores superiores a 10 cm. Finamente, se destaca que el volumen de datos generados durante los ensayos de fatiga y su procesamiento por medio de algoritmos desarrollados en la investigación permitieron abordar conceptos de energía disipada, como aproximación a la definición de criterios de micro y macro fractura que mostraron la utilidad de este tipo de metodologías para estudios futuros.

Optically transparent carbon based nanomaterials including graphene and carbon nanotubes(CNTs) are promising candidates as transparent conductive electrodes due to their high electrical conductivity coupled with high optical transparency, can be flexed several times with minimal deterioration in their electronic properties, and do not require costly high vacuum processing conditions. CNTs are easily solution processed through the use of surfactants sodium dodecyl sulfate(SDS) and sodium cholate(SC). Allowing CNTs to be deposited onto transparent substrates through vacuum filtration, ultrasonic spray coating, dip coating, spin coating, and inkjet printing. However, surfactants are electrically insulating, limit chemical doping, and increase optical absorption thereby decreasing overall performance of electrodes. Surfactants can be removed through nitric acid treatment and annealing in an inert environment (e.g. argon). In this thesis, the impact of surfactant removal on electrode performance was investigated. Nitric acid treatment has been shown to p-dope CNTs and remove the surfactant SDS. However, nitric acid p-doping is naturally dedoped with exposure to air, does not completely remove the surfactant SC, and has been shown to damage CNTs by creating defect sites. Annealing at temperatures up to 1000°C is advantageous in that it removes insulating surfactants. However, annealing may also remove surface functional groups that dope CNTs. Therefore, there are competing effects when annealing CNT electrodes. The impacts on electrode performance were investigated through the use of conductive-tip atomic force microscopy, sheet resistance, and transmittance measurements. In this thesis, the potential of graphene CNT composite electrodes as high performing transparent electrodes was investigated. As-made and annealed graphene oxide CNT composites electrodes were studied. Finally, a chemical vapor deposition grown graphene CNT composite electrode was also studied.